Since the switch to using regmap this function no longer takes the
I2C client struct as argument nor do we even interact with the client
anywhere other than when creating the regmap.

Rename it to a less misleading name: "rx8010_init()".
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200917114656.9036-1-brgl@bgdev.pl